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一、前言 稻草是水稻生产的副产品,我国水稻产量占世界第一位,播种面积达5亿多亩,平均单产500斤,按谷草比1:1计稻草总量达2,500亿斤。稻草除其它用途外,还由于含有大量有机物及各种作物养分,还田作肥料可以改良土壤理化、生物性质,扩大养分生物循环,促进作物生长。水稻利用的钾素,70％以上留在稻草中。2,500亿斤稻草中钾素折成标准肥达到450万吨,为我国1977年统计的钾肥产量的1.5倍。此外,稻草含有35～40％的纤维素,还有氮、磷,等其它养分,可见稻草是我国的一项重要资源。美国水稻产量只及我国的二十二分之一,但对秸杆还田的研究已有五、六个世纪之久。七十年代初日本总施肥量中化肥达到95％,由于土壤肥力出现问题而重视稻草还田的实践和研究。日本南方一些地区稻草有66％还田,他们对稻草与作物营养和土壤的肥力关系,也进行了广泛深入的研究。
I. INTRODUCTION Straw is a by-product of rice production. China’s rice output accounts for the largest in the world with a planting area of 500 million mu and an average yield of 500 kg. According to the 1: 1 ratio of straw to straw, the total amount of straw reached 250 billion kg. In addition to other uses, straw also contains a large amount of organic matter and various crop nutrients. Returning straw to soil can improve soil physicochemical and biological properties, expand the nutrient cycle and promote crop growth. More than 70% of the potassium used by rice remains in the straw. 250 million kilograms of straw in potassium into standard fertilizer reached 4.5 million tons, for our country in 1977 statistics of potash production 1.5 times. In addition, straw contains 35-40% of cellulose, as well as nitrogen, phosphorus, and other nutrients, shows that straw is an important resource in our country. The output of rice in the United States is only one-twelfth of China’s total output. However, research on straw returning has been going on for five or six centuries. The total amount of fertilizer in Japan in the early 1970s reached 95% of chemical fertilizers, due to problems with soil fertility and pay attention to the practice of straw and research. 66% of straw in some parts of southern Japan have been returned to the field. They also conducted extensive and in-depth studies on the relationship between straw and crop nutrition and soil fertility.